Composite lightweight barrel with predetermined thermal characteristics



Oct. 17, 1961 A. HAMMER 3, 61

COMPOSITE LIGHTWEIGHT BARREL WITH PREDETERMINED THERMAL CHARACTERISTICS Filed Oct. 8, 1959 2 Sheets-Sheet 1 a -Fmq 1 T INVENTOR. Alexander Hummer 1%. 2,12% 9 ad. W

ivunxdqlu Oct. 17, 1961 A. HAMMER 3,004,351

COMPOSITE LIGHTWEIGHT BARREL WITH- PREDETERMINED THERMAL CHARACTERISTICS. Filed Oct. 8, 1959 2 Sheets-Sheet 2 INVENTOR. Alsxnn Hrs: Hummer Ell,

United States Patent 3,004,361 COMPOSITE LIGHTWEIGHT BARREL WITH PRE- DETERMINED THERMAL CHARACTERISTICS Alexander Hammer, Springfield, Mass., assignor to the United States of America as represented by the Secretary of the Army Filed Oct. 8, 1959, Ser. No. 845,293 3 Claims. (Cl. 42--76) (Granted under Title 35, US. Code (1952), sec. 266) The invention described herein may be manufactured and used by 'or for the Government for governmental purposes without the payment of any royalty thereon.

This invention relates to firearms and more particularly to the structure of the barrels thereof.

Some of the major problems to be overcome in the design of firearms have to do with the adverse affects of the heat created by the discharge of cartridges therein.

It is well known that the walls of firearm'barrels are much thicker than is necessary to Withstand the pressures created by the discharge of cartridges therein. The extra wall thickness is provided to prevent deformation of the barrel through accumulated heat and to dampen the vibrations therein produced during operation of the firearm. This increased thickness, however, is not an entirely satisfactory solution of the problems because of the weight which is added thereby to the weapon and because with an increase in the thickness bf the barrel walls there is a proportionate increase in temperature gradients therein which cause stresses that often times result in barrel rupture.

The high temperature reached in the barrel during frequent firing also makes it necessary to provide some means whereby the barrel may be handled by the operator without discomfort or injury and these guard and handling means result, of course, in increasing the weight and bulk of the weapon.

It is, therefore, an object of this invention to provide a firearm barrel in which the weight is reduced by recessing longitudinal grooves along the periphery to form a core in which the cross-sectional area is reduced in thickness to only that sufiicient to withstand the pressure produced by the discharge of cartridges therein with sufficient rigidity being provided to prevent thermal deformation, of the barrel and reduce discharge vibrations therein by the longitudinal ribs formed by the grooves and inlays of lightweight material integrally formed in the grooves.

It is another object of this invention to provide such a barrel structure wherein the inlays are formed from material having a preselected coefficient of heat transmission to vary the thermal characteristics of the barrel.

It is still another object of this invention to provide such a barrel structure wherein the inlays are formed by longitudinal laminations or strands to increase the rigidity of the barrel.

It is another and still further object of this invention to provide such a barrel structure wherein the inlays are formed from material having a higher coefficient of heat transmission than steel so as to act as pumps in drawing heat from the core and discharging it by radiation to the atmosphere.

It is still another object of this invention to provide such a barrel structure wherein the inlays are formed by strands wound around the ribs and bonded together and to the core to give longitudinal rigidity thereto.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

FIG. 1 is a vertically sectioned side view of a barrel with aluminum inlays;

Patented oct. 17, 1961 FIG. 2 is a section taken along line 22 of FIG. 1; FIG. 3 is a fragmentary section of FIG. 1 enlarged to. show the laminated construction of the inlays;

FIG; 4 is a side view ofa barrel with glass fiber inlays v V with the-sheath partially broken away;

FIG. 5 is a view taken along line 5-5 of FIG. 4 with theinlays removed from the front end to show the con struction of the passageway around the front end of'the' ribs;

FIG. 7 is a reduced perspective view of the core of the barrel-shown in FIG. 4. J

Shown in'FIG. 1 is a firearm barrel 12 having a steel core 14 provided'with a cartridge'chamber 16 and. a,

rifled bore 18 extending coaXially forward therefrom. The outside surface fofvcore 14 is interrupted by a plurality oflongitudinally disposed grooves 20 which reduce the weight of the core by reducing the thickness of the walls thereof to only that suflicient to withstandthe pres-r the muzzle and breech ends thereof, resp ectively. Four of the grooves 20 are provided in the;present embodiment but this number may be varied according to the size of core 14. Formed by the grooves 20 are an equal numberof longitudinal ribs 26 which a ssist in rigidizing core 14 so as to withstand without deformation the maxi- V mum heat to which it will be subjected according to the predetermined function of barrel 12 and to also dampen excessive discharge vibrations therein. a

The grooves 20 are filled to complete the circular cross-section of barrel 12 by inlays 28 which are formed as hereinafter described of aluminum or other metal having a higher coeflicient of heat transmission and a lighter weight than steel so that barrel 12 will have a fighter weight than if made entirely therefrom. The inlays 28 are formed by electroplating the metal to the surfaces of the grooves 20 with the plating being applied by longitudinal sweeps of the depositing electrode to produce a layer upon layer or laminated-like construction. By being integrally bonded to the surfaces of the grooves 20 and being of laminated construction, the inlays 28 aid the ribs 26 in rigidizing core 14. Moreover, as the inlays 28 have a higher coefficient of heat transmission than core 14, the heat therein is drawn by convection therefrom and dissipated to the atmosphere by radiation, and the rate of transmission is increased by the area of contact between the inlays and core being increased by the arcuate configuration of the grooves '20. In other words, the inlays 28 act as pumps for drawing the heat from core 14 and discharging it to the atmosphere.

Shown in FIGS. 4-7 is a barrel 30 which is essentially the same as barrel 12 and which includes a core 32 having a plurality of peripheral grooves 34 which form a corresponding number of longitudinal ribs 36. However, in core 32 the portions of the ribs 36 in contact with the terminal arcuate portions of the grooves, which are represented at 22 and 24 in barrel 12, are removed to form with such arcuate portions a front conical portion 38 and a rear conical portion 40 which provide communication around the front and rear ends of the ribs between the grooves 34 on opposite sides of each thereof. In barrel '30, the grooves 34 are filled by inlays 42 which are composed of a plurality of longitudinally disposed strands 44 fabricated from glass fibers or other material having lighter weight and a lower coefficient of heat transmission than steel. The inlays 42 are formed by winding the strands 44 around each of the ribs 36 FIG. 6 is a view taken along line 6-6 of FIG. 4; and i 3 by means of the conical portions 38 and 40 until the grooves 34 and conical portions are filled with the adjacent strands beingbonded together and to the surfaces of the grooves and conical portions by suitable bonding material and method. Thus, core 32 is rigidly supported by-the inlays42 in c ooperation with the-ribs 56. Also, becausestrands 44 are fabricated 'from material-having a lower coeflicient of heat 'transmission than"steel, the:

rate 'of heat 'transmissionfrom'the bore of barrel 30 to the outside thereof is reduced. A sheath 46*fabricated from the samematerial as the strands 44 is producedto envelopecore 32 and thereby cover theoutside surfaces of the-ribs 36; Thus, barrel 30 may be handled without discomfort or injury when used with firearms operable inshort bursts and slower rate of fire as a shoulder arm;- I

It is obvious that strands 44 and sheath 46'may be fabricated. from a material which has a higher coefiiciency ofheat transmission than steel wheredis'sipation of heat from barrel 30 is of prime importance.

Although only two embodiments of the invention have been-described in detail herein, it is evident that many variations'rnay be devised within the spiritfandiscope thereof and the following claims are intended to include such variations.

I claim:

1. A barrel includinga steel core providedwitha periphery of said core to reduce the'cross-sectional thicksaid -layers being integrally bonded'to the walls'of said grooves and to each other "toproduce laminated-type inlays which fill said grooves and are integral with said core.

2. The barrel-as defined in claim 1 Whereinsaid laminated-type inlays are formed by a plurality of superposed layers deposited by electrochemical process along said grooves.

3. A barrel including a steel core having a cartridge chamber 'anda coaxial bore, a plurality of peripheral grooves extending longitudinally along said core for reducing'thecross-section thickness thereof to thatonly suf-' ficient to withstand the pressure produced in the bore and chamber by jthe discharge :of a cartridge-therein, longitudinal ribs formed -by said groovesya [pair of recessed conical portions longitudinally spaced in said core to terminate the front and rear ends of said ribs and providecommunication between said grooves-on opposite sides ofeach'thereofl a strand'of a material lighter ini weightthan'steeland having a coefliciency of heat trans-- mission-selected to obtain desired thermal characteristics in the barrel, a plurality of continuous turns .formed:

from said strand around 'eachof said ribs to fill'said grooves andsaid pair of conical portions, said turnsbeing bonded to each other and to the walls of the:asso-1 ciatedone of said grooves to form in ea'chthereof an in- -'lay integral with saidcore:

ReferencesCited inztherfile of this p atent UNITED STATES PATENTS I 618,036 Hurst Jan. 17, 1899 2,112,144 Coupland Mar. 22, 1938 2,687,591 Lamb et al Aug. 31, 1954 2,692,851 Burrows Oct. 26,1954 2,845,741 Day Aug. 5,1958

1 2,847,786 Hartley et al Aug. 19, 1958 FOREIGN PATENTS 1 127,264 Great Britain June 5, 1919 369,782 Great Britain Mar.3l, 1932 1 

